Recently, significant attention has been focused on televisions and monitors that offer a larger and clearer viewing picture to a viewer. Such large screen devices typically use a large piece of sheet glass for the viewing surface. Pulling rolls are used in the manufacture of this sheet glass to apply tension to the ribbon of glass from which the sheets are formed, and thus to control the nominal sheet thickness. Typically, producing a pulling roll can take several hours. Pulling rolls are typically made from roll material, such as millboard, which is punched to produce disks that are fired and then pressed onto shafts to produce the pulling roll. These pulling rolls are subsequently cut on a lathe to a particular surface finish and are then contoured for installation into machines used in the production of sheet glass. If a pulling roll ultimately fails to meet certain standards for material properties (e.g., hardness), the roll must be taken apart and rebuilt. Because a set of two pulling rolls must be made with a single lot of material, if the material is unacceptable this results in significant losses in time and cost.
Typically, the roll material is purchased according to broad material specifications, but there is no existing means of testing the incoming material under the conditions that it will be under when manufactured into pulling rolls. For example, when extreme pressure is applied to the pulling rolls, the material properties of compressibility, recovery and resiliency are of concern. In addition, the hardness of the material is of concern as a measure of how well the roll will endure thermal conditions and interface with the glass during production. If a lot of millboard material does not meet the desired specifications, this failure will be unknown until the pulling rolls have been manufactured and put to use. This results in significant losses in both time and cost.
Thus, there is a need in the art for methods and systems for evaluating the properties of material to be used in the manufacture of pulling rolls prior to the production of these pulling rolls.